An active optical cable is an optical fiber cable that is terminated on one or both ends with an AOC connector that contains an optical transceiver module. The AOC connector has an AOC connector housing that is typically configured to be received within an opening formed in a receptacle. The AOC connector typically includes an optical connector that is permanently attached to the end of the optical fiber and to the AOC connector housing. Mechanical coupling features on the AOC connector housing form a latch that interlocks with mechanical coupling features on the receptacle to secure the AOC connector to the receptacle. The receptacle may be, for example, an opening formed in a cage. When the AOC connector is fully inserted into the receptacle, the latch of the AOC connector housing engages one or more of the mechanical coupling features of the receptacle to lock the AOC connector housing inside of the receptacle. The latch of the AOC connector housing is typically operable by a user to be placed in a delatching position to enable the user to remove the AOC connector housing from the receptacle.
FIG. 1 illustrates a top perspective view of a known Quad Small Form-Factor Pluggable (QSFP) AOC 2 currently used in the optical communications industry. An optical fiber cable 3 of the QSFP AOC 2 includes a plurality of transmit optical fibers (not shown for purposes of clarity) and a plurality of receive optical fibers (not shown for purposes of clarity). The cable 3 has an optical connector 3a secured to an end thereof, which, in turn, is secured to an AOC connector 4 of the AOC 2. The AOC connector 4 has an AOC connector housing 5. The aforementioned optical transceiver module (not shown for purposes of clarity) is housed within the AOC connector housing 5. The AOC connector housing 5 includes a first housing portion 5a and a second housing portion 5b, which are connected together by fastening elements (not shown for purposes of clarity). The first and second portions 5a and 5b of the housing 5 are typically made of metal, such as cast aluminum, cast zinc, or a cast zinc alloy.
A delatch device 6 of the AOC connector 4 allows the housing 5 to be delatched from a cage (not shown for purposes of clarity) to enable the housing 5 to be removed from the cage. A pull tab 7 is connected on its proximal end 7a to the delatch device 6. When a user pulls on the distal end 7b of the pull tab 7 in the direction indicated by arrow 8, slider portions 6a and 6b of the delatch device 6 move to a limited extent in the direction indicated by arrow 8 (only slider portion 6a can be seen in FIG. 1). This movement of the slider portions 6a and 6b causes outwardly curved ends 6a′ and 6b′ of the slider portions 6a and 6b, respectively, to press against respective catch features on the cage (not shown for purposes of clarity) to allow the connector housing 5 to be retracted from the cage.
The majority of AOCs currently used in the optical communications industry have configurations that are similar to that of the QSFP AOC 2 shown in FIG. 1, although other types of AOCs having other form factors are also used in the industry. In QSFP AOCs of the type shown in FIG. 1, the optical transceiver module housed in the housing 5 typically includes parallel arrays of electrical-to-optical (EO) conversion elements (e.g., lasers or light-emitting diodes (LEDs)), parallel arrays of optical-to-electrical (OE) conversion elements (e.g., photodiodes), and parallel laser driver and receiver integrated circuit (IC) chips. These parallel components are mounted on an upper surface of a printed circuit board (PCB) 9. The parallel components are relatively expensive due in large part to the fact that a high degree of uniformity is typically required among the EO conversion elements. In addition, the parallel components used in these modules are manufactured in relatively low volumes, and thus generally have higher costs associated with them.
AOCs that have a single EO conversion element and/or a single OE conversion element are also known. In such AOCs, the cable contains at least one optical fiber. Like the QSFP AOC described above with reference to FIG. 1, such AOCs have a AOC connector housing and an optical connector that permanently attaches to the end of the cable and to the AOC connector housing. The AOC connector housing can take on a variety of forms, but typically comprises some type of encapsulation. The EO and/or OE conversion elements, the leadframe, and the metal bond wires that connect the EO and/or OE conversion elements to the leadframe are encapsulated within the encapsulation. The AOC is only capable of operating over a limited range of temperatures due to the fact that the encapsulation, which is typically made of epoxy, has a very different coefficient of thermal expansion (CTE) than metal. Therefore, the epoxy encapsulation expands and contracts at different temperatures than the metal bond wires, which places stress on the metal bond wires. This stress can cause the metal bond wires to break. Consequently, the operations of the AOC may be limited to a relatively small range of temperatures (e.g., 0 to 80 degrees Celsius (C)) and to a relatively small number of temperature cycles (e.g., 200).
One disadvantage of AOCs of the type described above is that they use optical connectors. These optical connectors often have relatively large form factors. For example, the optical connector may be a larger version of the well known LC connector. Such optical connectors are relatively expensive to produce and consume a large amount of space. Therefore, the use of such optical connectors in AOCs tends to increase the overall costs of AOCs.
Accordingly, a need exists for an AOC that does not include an optical connector and therefore has an overall cost that is less than that of known AOCs that are currently available in the market. A need also exists for a relatively low-cost AOC that is capable of operating over a relatively broad range of temperatures and over a relatively large number of temperature cycles.